ENGINEERING OF LIGHTWEIGHT CERAMIC COMPOSITES BY SPARK PLASMA SINTERING

摘要

It is well recognised that value of porosity and grain size influences mechanical properties such as fracture toughness, elastic modulus and strength dramatically. Boron carbide (B_4C), as well as other lightweight ceramics like TiB_2, B_6O requires high consolidation temperatures owing to its poor sinterability. Therefore such decrease of ceramics properties becomes a materials processing issue since during consolidation process on the final stage of sintering (either pressure-assisted or pressureless one) grain growth starts. To overcome this problem, various metallic and non-metallic binders are used to obtain dense borides. However, the presence of a metallic binder is not desirable for high-temperature structural applications. We propose that reaction-driven consolidation by means of spark plasma sintering (SPS) at temperatures exceeding 1800 ℃ as an alternative method for fabrication of high-temperature lightweight ceramic composites.